Mercoid switch



Dec. 28, 1937. J, MCA, HARRls, JR 2,103,459

IIIIIIIIIIIII CH Dec. 28, 1931. J. m. HANS, JR 2,1 3,

MERCOID SWITCH Filed Sept. 14, 1935 2 Sheets-Sheet 2.

Patented Dec. 28, 1937 PATENT OFFICE} MEECOID SWITCH John McArthur Harris, Jr., Baton Rouge, La.,

assignor to Standard Oil Development Company, a corporation of Delaware Application September 14, 1935, Serial No. 40,575

1 Claim.

This invention relates to improvements in a switch of the type in which mercury is used to make and break connection between electrical conductors.

The invention will be fully understood from the following description taken in connection with the accompanying drawings, in which latter Fig. 1 is a longitudinal sectional view through a preferred form of switch showing the plunger in its elevated position;

Fig. 2 is a longitudinal sectional view of the device of Fig. 1 showing the plunger in its depressed position with the solenoid energized;

Fig. 3 is a longitudinal sectional view through the device showing the solenoid in elevated position and the plunger held by the solenoid in elevated position; and

Fig. 4 is a longitudinal sectional view of the device of Fig. 3 showing the plunger in its lowered position with the solenoid de-energized.

Referring particularly to Figs. 1 and 2 of the drawings the device comprises a sealed envelope having depending wells 3 and 4. The wells 3 and 4 contain a column of mercury 5 and 6 respectively. Alternatively, other electrical conductive liquid can be used instead of mercury and some of the advantages of the invention will be retained. Lead wires formed of tungsten or the like, and designated 8 and 9, pass through the walls of the wells 3 and 4 respectively in contact with the column of mercury contained therein.

A plunger ii is mounted for vertical reciprocation within the envelope i. The plunger comprises a float member I2 which is supported by the mercury 6 within the well 4. A magnetic member II is disposed within the plunger II. The plunger II is preferably formed of glass, such as'pyrex glass. A solenoid l6 having leads I! encircles the envelope l in position, when 50 so that closing the circuit through the solenoid in Figs. 1 and 2 the level of mercury in the well 4 is so adjusted that with the plunger ii floating inthe column of mercury 6, the level 24 of the column 6 is below the bottom wall- 26 of the opening between the wells 3 and 4, so that there 5 is no electrical connection between the mercury columns 5 and 6 when the solenoid I6 is de-energized. The solenoid I6 is positioned slightly below the magnetic member l3, whereby .when current is passed through the solenoid the 10 plunger is drawn down in the mercury 6 and the switch is closed, as illustrated in Fig. 2.

Referring particularly to Figs. 3 and 4 of the drawings, the'device is illustrated with a portion of the mercury 23 within the mercury reservoir 2| poured into the well 4, leaving only a small volume of mercury 30 within the reservoir 2i. In order to operate this form of the invention the solenoid i6 is elevated with respect to the magnetic member l3, so that when current is passed through the solenoid 16 the plunger II is maintained in elevated position withdrawn from the column of mercury 6 within the well 4, as is illustrated in Fig. 3. In this position the level 24 of the column of mercury 6 is below the bot- 25 tom wall 26 of the opening between the wells 3 and 4. Consequently there is no electrical contact between the columns of mercury 5 and 6.

On de-energizing the solenoid i6 the plunger i l drops, partially submerging the float i2 within the column of mercury 6 and effecting over-flow of the column of mercury 6 into the well 3, causing a layer of mercury 20 to connect the columns of mercury 5 and 6, as previously described in connection with Figs. 1 and 2;

The plunger II and columns of mercury 5 and 6 are sealed in the pyrexglass shell I, which has previously been filled with moisture-free hydrogen gas at a pressure slightly below atmospheric pressure, such as 700 mm. pressure. The magnetic member l3 within the pyrex glass plunger is preferably a soft iron core which is sealed into the plunger. Since the soft iron core is sealed into the plunger it is not necessary to de-gas the core when evacuating the envelope I preliminary to filling the envelope i with hydrogen gas. Any oxygen retained in th iron core is prevented by the plunger from uniting with the hydrogen to form water, which would corrode the iron and foul the surface of the mercury. Similarly, the sealed iron core is prevented from getting in contact with the electric arc at the make and break of the circuit and small pieces oi! iron are prevented from being knocked off into the mercury. Since the make and break is through the liquid there is no wearing away of the liquid surface caused by an electric'arc. The construction de-- scribed is relatively simple. It has no moving parts which are exposed. The device does not An electric switch of the liquid flow type comprising a sealed tubular envelope having depending wells communicatin with each other through the envelope, a column of mercury in each well, an electrode in each well in contact with the mercury, a plunger comprising a magnetic meme 7 ber enclosed in non-porous material-and mounted for longitudinal movement in the mercury of one of the wells, a solenoid for effecting movement of the plunger whereby in one position the plunger is lowered displacing a portion of the mercury in the last-mentioned well to cause overflow of the mercury into the other well and establish an electric circuit through the columns of mercury between the electrodes, and a reservoir containing mercury communicating with the envelope whereby the quantity of mercury in the wells can be varied to either cause the plunger to close the circuit by moving it into the well or by withdrawing it from the well.

JOHN McARTHUR HARRIS, JR.

CERTIFICATE OF CORRECTION Patent No. 2,105,L .59.

December 28, 1927 Jon-N McARTHUR HARRIS, JR.

' It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: In the grant 5 line 6, title of invention, for "MERCOID SWITCHES I'Qad MERCURY SWITCHES; and in the heading tovthe printed specification anddrawings for MERCOID SWITCH" read NERCURX SWITCH; and that the Said Letters Patent should be read with these corrections therein that the same may conformto the record of the case in the Patent Office.

Signed and sealed this 1st day of March, A. D. 1958.

(Seal) Henry Van Arsdale, Acting Commissioner of Patents. 

